A known auxiliary powered bicycle has a drive wheel to which a motor is connected. When the bicycle is driven by manpower, the motor is driven in accordance with the load applied to the pedal. This produces auxiliary power that supplements the manpower. Thus, the bicycle can be driven with a low degree of manpower.
Japanese Unexamined Patent Publication No. 4-100790 describes an example of how to measure the drive force applied by man. A torsion bar is used as a pedal crank axle. A detector such as a potentiometer or a strain gauge is arranged on the torsion bar to detect the twisted amount of the torsion bar and thus measure the applied torque.
However, the potentiometer or the strain gauge is arranged on a rotated axle. Thus, signals representing the detected value must be output using a slip ring or a brush. As a result, there is a tendency for noise to be included in the signals due to friction and abrasion. This makes it difficult to detect torque accurately.
In addition, the employment of a slip ring or a brush produces aural noise caused by friction as the bicycle moves. Such noise may make the rider feel uncomfortable.
Furthermore, the slip ring and the brush must be replaced when abrasion occurrs. Such replacement is burdensome.
Accordingly, it is an objective of the present invention to provide an auxiliary powered manpowered vehicle having a torque detector that detects the torque applied to a rotated crank axle in a non-contact manner in order to prevent the production of noise caused by friction or abrasion and detect torque accurately.
It is a another objective of the present invention to provide an auxiliary powered manpowered vehicle that prevents the production of aural noise due to friction when the bicycle travels and thus does not make the rider feel uncomfortable.
It is also an objective of the present invention to provide an auxiliary powered manpowered vehicle that prevents abrasion between parts and thus eliminates the necessity for the replacement of such parts.
It is a further objective of the present invention to provide an auxiliary powered manpowered vehicle that detects a load acting along the rotating direction of a crank axle and a drive gear within the same plane and thus uses restricted space in an effective manner.